Please help. Sewer gas smell only at night, only January-March

[toughproblem]

The air conditioner and furnace both drain into the same cpvc line, which goes to a single ptrap which has water in it.

 

[frodo]

ok,,,,we beat the heat unit to death,




if not dry traps...then it may be a trap that is being back syphoned dry


did your plumber check that

 

[toughproblem]

ok,,,,we beat the heat unit to death,




if not dry traps...then it may be a trap that is being back syphoned dry


did your plumber check that

He is due to arrive in a few minutes, I will be sure to ask him

 

[toughproblem]

He is due to arrive in a few minutes, I will be sure to ask him

All the traps looked normal. None of the side plugs we tried would fit, as the hole is slightly bigger than 1.5" apparently, and the ABS cap wouldn't thread in because the threads are all rounded over.

I ordered a 1.5" Test Titan which should be here Thursday. Will keep you in the loop.

 

[frodo]

what i am talking about is back siphonage.

a condition that is cause by a blocked or no vent.

when you use the sink, or toilet, or washer, the water in the trap gets "pulled" out due to siphonage.

you are useing the sink/toilet/ washer. so you assume, the trap has a water seal.

follow me ?

 

[toughproblem]

what i am talking about is back siphonage.

a condition that is cause by a blocked or no vent.

when you use the sink, or toilet, or washer, the water in the trap gets "pulled" out due to siphonage.

you are useing the sink/toilet/ washer. so you assume, the trap has a water seal.

follow me ?

I think I follow you, but if something was back siphoning, wouldn't the trap go temporarily dry during the flush/sink drain/washer, and then return when the temporary drain run completes?

 

[frodo]

no...


not saying this is happening, but it is a distinct possibility

 

[toughproblem]

no...View attachment 11007


not saying this is happening, but it is a distinct possibility

I see, thank you for the picture. I can see water in the traps so I do not think that is happening.

 

[Mr_David]

The most illusive odor problem I had to deal with was in a commercial property.
I had been out several occasion. crawled through attic. checked roof.
when I should up the odor was not noticeable.
I think it was when the urinal in a nearby bathroom got flushed it sucked the water out of the kitchen p-trap.

Time to go night-night. I fell asleep at the keyboard. Good thing I wasn't driving

 

[toughproblem]

The most illusive odor problem I had to deal with was in a commercial property.
I had been out several occasion. crawled through attic. checked roof.
when I should up the odor was not noticeable.
I think it was when the urinal in a nearby bathroom got flushed it sucked the water out of the kitchen p-trap.

Time to go night-night. I fell asleep at the keyboard. Good thing I wasn't driving

It will smell whether we are there or not though. We have left the house with nothing running, no washing machines or dishwashers and returned hours later to a strong smell.

 

[toughproblem]

Update: I managed to trim down a 2" wing-nut style mechanical test plug and get what feels like a tight seal on the side plug. I opened the windows for an hour to make sure everything was aired out. Tonight will be a good test as it's around 9F outside right now.

 

[toughproblem]

Update: The main floor washing machine drain did not have a p-trap on it, we found that out by issuing a smoke test, and the entire laundry system filled with smoke. We cut away the drywall to verify there was no p-trap and added a p-trap.

The side-plug (cleanout plug) in the basement floor drain near the furnace was leaking smoke. We replaced it with a galvanized plug with teflon and paste, and then siliconed around it.

Unfortunately the weather is getting warmer so I'm unsure if I'll be able to verify it's fixed until next January. We will see.

 

[Mr_David]

WOW. NICE. Glad you found it an Thanks for the update.

 

[toughproblem]

I think I still have a small problem with the side-plug on that problematic floor drain, even though we fitted a galvanized plug and siliconed around it. There is a very faint smell in the basement right now (9PM), which has developed over the last few hours. How do you recommend I proceed? The 1.5" test plugs were too small and the 2" were too big. I have a test titan 1.5" on order, as those seem to be a little bigger than 1.5", but do you have recommendations for other ideas in the mean time, or in case it doesn't work?

 

[Titaniumplumber]

Plate o **** in your wall

 

[frodo]

blow up test ball, make DOUBLE damn sure, you secure that ring to something.
it if looses air, it will drop into the pipe. you F---up if that happens

 

[toughproblem]

I put a piece of 1mil plastic over the entire drain and gorilla taped it to the floor.

As a test. I will not leave it like that permanently.